The basic feature of Toulmin's conception of rationality was that he refused to identify it with formal logic. Rational behavior and thinking was for him such that managed to register a change in the environment and respond to it by an adaptation. Such a way of thinking, however, was not always obvious to science. Toulmin thus joined the group of philosophers of science, as were K. R. Popper or T. S. Kuhn, who also criticized the earlier conception of rationality. This is not to say that he agreed with them in all. Especially in his book Cosmopolis, Toulmin investigated when the criticized way of thinking in science (but in a way also in society) enforced. He concludes that this break came about between the 16th and the 17th century, when the older way of thinking, which points out especially at Montaigne, made concessions to the new way of thinking which is far stricter and particularly intolerant. Toulmin suggests going back to certain elements of Renaissance humanism and its manner of discussion. In a way, he does it when interpreting the development of science. Hereby he are mainly criticizes Kuhn for his concept of scientific revolution. He takes as a pattern of thinking Darwin‘s theory and, in a way, Anglo-Saxon law based on precedents, or even technical thinking. The problem of development forces Toulmin to address the issue of continuity and changes in scientific thinking. He explains this by a help of the concept of scientific discipline in order to arrive at the fact that even this particular concept is an application of cultural universals in cultural anthropology of science. – Toulmin wrote during the boom of postmodernism. His merit is that although responded to a number of issues that postmodernists encountered, he could cope with them in a different (more acceptable) way than they did.